Near the end, a vampire serial killer explains that he lived in a hippie commune in California in the 60's and that drugs, free love and Joni Mitchell music made him what he is! He adds that a lot of the communes at that time had vampires in them.

Colin transcribed the Joni content in the following dialogue:

William shrugged.'Oh, we've always been here. This used to be a commune - California-dreaming hippies, mind-altering drugs, Joni Mitchell music. Our parents were hippies. We were isolated from other ways to live and think, so we depended on each other. My brother and I are unbelievably close. But we're nothing really. We're here to serve the Sire.'

And Janine adds that this book is part of Patterson's Alex Cross series.